/**
 * 图片blob转图片base64
 * @param blob
 */
export function blobToBase64(blob) {
  return new Promise((resolve, reject) => {
    const fileReader = new FileReader()
    fileReader.onload = (e) => {
      resolve(e.target.result)
    }
    // readAsDataURL
    fileReader.readAsDataURL(blob)
    fileReader.onerror = () => {
      reject(new Error('blobToBase64 error'))
    }
  })
}

/**
 * 图片base64转blob
 * @param base64 base64图片
 */
export function base64ToBlob(base64) {
  let bstr = window.atob(base64);
  let n = bstr.length;
  let u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n)
  }
  return new Blob([u8arr], { type: base64 })
}
